1. Field of the Invention
The present invention relates to a recording solution, and an ink-jet recording method making use of the solution. More particularly, it relates a recording liquid capable of giving a recorded image with a superior tone sharpness, light-resistance and gas resistance, and an ink-jet recording method making use of this liquid.
2. Related Background Art
Hitherto having been used as inks in writing utensils such as fountain pens and felt pens are recording liquids comprising various types of dyes dissolved in water or other organic solvents.
Inks comprising various types of dyes dissolved in water or other organic solvent are also used in ink-jet systems in which recording is performed by ejecting ink from an ejection orifice provided in a recording head, by the action of the oscillation attributable to a piezoelectric oscillator or the electrostatic force attributable to the application of a high voltage. The inks for ink-jet systems, however, are required to satisfy more severe conditions with respect to many performances than those required in the writing utensils such as fountain pens and felt pens commonly used.
The ink-jet systems make less noise and can perform high-speed recording or color recording on plain paper without taking any particular fixing step, and researches have been energetically made on various types.
Various methods are available for systems of this type, but all of them are required to have the performances such that the physical properties such as viscosity and surface tension are within the range of suitability, the recording agent has a dissolution satability high enough not to cause clogging of the minute ejection orifice, a recorded image can be obtained in a sufficiently high density, and changes in the values of physical properties, precipitation of solid contents, or the like may not occur during storage.
In addition to the above performances, they are also required to have the properties that the recording can be performed without limitation on the type of recording members, they can achieve a high fixing speed, and they can give a recorded image with excellent water resistance, solvent resistance (resistance to alcohol, in particular), light-resistance, wear resistance, and resolution.
Among these, particularly in relation to magenta color recording, recorded images tend to undergo color fading by light irradiation, in other words, have a poor light-resistance, causing a great problem. Thus, inks improved to eliminate these disadvantages have been strongly sought.
From such viewpoints, many proposals relating to inks have been made. For example, Japanese Patent Application Laid-Open No. 57-30773, No. 63-46259 and No. 63-46260 propose to use monoazo metal complex dyes. Such metal-containing dyes, however, involve the disadvantages that they lack tone sharpness, and have a poor color reproducibility when a color image is formed. Moreover, records obtained using the metal-containing dyes (in particular, records made on a coated paper containing silica on its surface) commonly undergo color fading due to gas in the air in addition to the color fading due to light, when they are stuck on a wall in the room. This phenomenon is particularly remarkable when they are stuck near a copying machine. Because of the disadvantages involved as mentioned above, it is difficult to use the metal-containing dyes alone.
Japanese Patent Application Laid-Open No. 62-190275 proposes to use by mixture a monoazo metal-free dye achievable of a sharp tone and a monoazo metal-containing dye. This method can obtain a record which is good and well-balanced in both tone and light-resistance. However, the gas resistance as questioned in the above has not been satisfactorily improved.